Several methods are commonly used for controlling the output voltage for welders and various other kinds of equipment requiring adjustable power supplies. Examples are the tapped transformer and range selector switch, and the sliding brush variable transformer. More recently, silicon controlled rectifiers (SCRs) and other electronic devices have come onto the scene as more sophisticated forms of controls. There remains room for improvement of the less sophisticated versions, however, not only for cost reduction, but also for ease of servicing and repairing where electronic service is not readily available.
The workhorse of the welding equipment industry has long been the manually-operated range selector switch at the terminal ends of conductor wires which lead from locations where they are physically tapped to the secondary winding of a transformer. The transformer, switch and other controls are typically located within a housing, and a range selector switch handle is on the housing for ease of reach and operation by the welder. The present invention is designed to eliminate the need for a separate range selector switch, its contacts and the leads tapped to the transformer secondary winding.